Intro to TDD

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Transcript

1. INTRO TO TDD
2. WHAT IS TDD?
3. TEST DRIVEN DEVELOPMENT
4. "first the developer writes an (initially failing) automated test case that defines a desired improvement or new function, then produces the minimum amount of code to pass that test, and finally refactors the new code to acceptable standards." — Wikipedia
5. 1. WRITE A FAILING TEST
6. 2. PASS THE TEST
7. 3. REFACTOR
8. RED, GREEN, REFACTOR
9. WHY DO TDD?
10. SHORT FEEDBACK CYCLE
11. I COULD DO THIS...
12. OR I COULD DO THIS!
13. SMALLER PIECES
14. "even if I couldn't imagine an implementation I could almost always figure out how to write a test." Kent Beck
15. IMPROVE DESIGN
16. ▸ Be a client of your own code. ▸ If it's hard to write the test, rethink your code.
17. REFACTOR WITH CONFIDENCE
18. ▸ Stop avoiding old code because you are afraid of breaking it. ▸ Rework becomes enjoyable, not stressful.
19. WHY WRITE THE TESTS FIRST?
20. ▸ Demonstrates understanding of what it is we are going to do. ▸ Ensures we are testing the right thing.
21. LET'S GET STARTED!
22. There should be a method on Calculator called "add" that takes a string representation of a number ("1") and returns it as a number (1).
23. When I give the method an empty string (""), it should return 0.
24. require "minitest/autorun" require_relative "calculator" class TestCalculator < MiniTest::Unit::TestCase def test_given_string1_returns_1 assert_equal Calculator.add("1"), 1 end def test_given_string_returns_number number = rand(100) assert_equal Calculator.add(number.to_s), number end end
25. class Calculator def self.add(string) string.to_i end end
26. YOUR TURN!
27. SHARE YOUR SOLUTION!
28. FURTHER READING ▸ Test Driven Development on Wikipedia ▸ The Three Rules of TDD by Uncle Bob ▸ Test Driven Development from The Art of Agile Development ▸ Extreme Programming ▸ Test Driven Development By Example ▸ String Calculator Solution by ericroberts